Two new anthraquinone derivatives and one new triarylbenzophenone analog from Selaginella tamariscina

Abstract

Two new anthraquinone derivatives, selaginones A (1) and B (2), and one new triarylbenzophenone analog, selagibenzophenone B (3), were isolated from Selaginella tamariscina (Beauv.) Spring. Their structures were established by 1D-, 2D-NMR and HR-ESI-MS data. Compounds 1 and 2 represent the uncommon examples of aryl substituted anthraquinone derivatives. Especially, compound 2 is a unique anthranone with exceptional structural feature, in which a p-hydroxyphenyl moiety is attached to the C-10 position. Compound 3 is the second naturally occurring triarylbenzophenone and showed moderate activity against SMCC-7721 and MHCC97-H cell lines with IC₅₀ values of 39.8, 51.5 μM respectively.     

Thermodynamic properties of anthraquinone derivatives

The enthalpies of solution of a series of anthraquinone derivatives in dioxane at various dilutions were determined by isothermal calorimetry.     

Acidities of anthraquinone and its hydroxy derivatives

The acidities of anthraquinone and its 1- and 6-hydroxy derivatives were studied. It is shown that the anthrone ring in the anthrapyridone molecule displays a strong electron-acceptor effect that stabilizes the anion during the development in the pyridone ring of a negative charge as a result of ionization; as a consequence of this, anthrapyridone and 1-hydroxyanthrapyridone are considerably stronger acids than 2-pyridone and 3-hydroxy-2-pyridone, respectively.Communication VII from the series Structure and Properties of Dyes. See [1] for communication VI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1373–1376, October, 1978.     

Selective cyclodimerization of epichlorohydrin to dioxane derivatives over MOFs

Glycerol can be converted to valuable products such as epichlorohydrin which is an important intermediate applied in various industries. For example, dioxane derivatives, which are important pharmaceuticals, can be obtained from epichlorohydrin. In the present study, ZIF-8, ZIF-67, MIL-100, and UiO-66 were applied for the direct cyclodimerization of epichlorohydrin. These MOFs were selected because they were already applied as active catalysts in ring opening of epoxides. Among them, ZIF-8 showed the highest activity and selectivity in the absence of any solvent or co-catalyst. Using ZIF-8 as a catalyst, the cyclodimer product (1,4-dioxane 2,5-bis-chloromethyl) was obtained in a yield of about 70% which was significantly superior to previous homo or heterogeneous catalysts for this reaction. Due to ZIF-8 structure and the proposed mechanism, the cyclodimerization reaction catalyzed either by the defects in the structure and/or on the surface. Furthermore, acidic-basic characteristics were also in play. The NH₃ and CO₂ temperature-programed desorption technique were utilized to identify the active sites and thereby reaction mechanism. Moreover, because of similar properties of ZIF-8 to zeolites, the activity of commercial ZSM-5 for the same reaction was also investigated in this work.     

Synthesis of chiral oxa- and azacycle-fused anthraquinone derivatives

A convenient protocol for the synthesis of chiral pyran and piperidine ring-fused anthraquinone derivatives has been developed from (R)-2,3-O-cyclohexylidene-glyceraldehyde using sequential applications of enyne metathesis, Diels–Alder reaction and aromatization as key steps.     

Structures and tautomeric interconversions of anthraquinone imine derivatives

Substituted 1-hydroxy-9,10-anthraquinone-9-imines have been found to exhibit tautomeric interconversions between the 9,10- and 1,10-quinonoid forms in the solid state as well as in solution. Single-crystal X-ray crystallography was used to study the structures of 4-(N-acetyl-p-tolylamino)-9-amino-1,10-anthracenedione and 4-hydroxy-1-phenylamino-10-mesitylimino-9(10H)-anthracenone at ambient and low temperatures. The former compound gave crystals belonging to the monoclinic space group P2_l/c and, at 295 K,a=9.684(2),b=16.371(3),c=12.097(2) å,=110.41(1), V=1797 å³,Z=4, R(F)=0.042, and GOF=0.863. The latter compound gave crystals belonging to the monoclinic space group C2/c and, at 295 K,a=38.158(8),b=6.322(2),c=19.325(4) å,=101.78(2),V=4564 å³,Z=8, R(F)=0.052, and GOF=0.981, while at 150 K,a=37.852(6),b=6.245(1),c=19.235(4) å,=102.81(1),V=4434 å³,R(F)=0.047, and GOF=1.006. Comparison of the geometric parameters of the two compounds illustrates the considerable zwitterionic nature of the first, a distinctive feature of which is a very short bond N(9)-C(9) whose length is essentially equal to that of a double bond. Molecular modeling studies using AMI semiempirical calculations were shown to be capable of satisfactorily reproducing the energetics of the tautomeric equilibrium once the medium effect was taken into account.     

Two new anthraquinone malonylglucosides from Polygonum cuspidatum

Two new anthraquinone malonylglucosides polygonins A and B were isolated from Polygonum cuspidatum along with seven known compounds. The structures of 1 and 2 were elucidated based on their spectroscopic data.     

Substituent effects in the one-electron reduction of anthraquinone derivatives

Polarographic reduction against (C₂H₅)₄NBr as background in dimenthyformamide has been applied to 17 anthraquinones with - and -substituents. There are two pronounced half-waves, which correspond to two one-electron degrees of reduction, a semiquinone anion being formed as intermediate. An ESR signal is produced when this radical is formed by electrolysis with a cathode potential equal to E_1/2. The observed E_1/2 fit Hammett's equation closely. The relation E_1/2 to donor-acceptor aspects of the substituents is discussed.     

New anthraquinone derivatives from the roots of Berchemia floribunda

A new naphthoquinone-anthraquinone dimer named floribundiquinone E(1)and a new anthraquinone 2-acetylphyscion(2)were isolated from the roots of Berchemia floribunda Brongn.Their structures were elucidated on the basis of spectroscopicmethods.     

Spectrophotometric and spectrofluorimetric investigation of aggregation of some anthraquinone derivatives

The behaviour of some anthraquinone derivatives in aqueous solution has been studied by absorption and fluorescence spectrophotometry. The results point to the presence of molecular aggregates in solution, also confirmed by polarographic determinations.     

Photochemical studies: Chromones,bischromones and anthraquinone derivatives

Photochemical reaction is a chemical reaction initiated by the absorption of energy in the form of light resulting in different types of reaction. Chromones, bischromones and anthraquinones are the bichromophoric molecules which contain the carbonyl group and double bond in conjugation. Photochemical reactions of these compounds result in the formation of such molecules which are not obtained via conventional methods. This review article describes the photochemical transformations of chromones, bischromones and anthraquinone derivatives and here main emphasis has been laid upon the intramolecular photochemical H-abstraction reactions that provide many exotic heterocyclics as the final photoproducts.     

Preparations of anthraquinone and naphthoquinone derivatives and their cytotoxic effects

Chrysophanol and 1,8-di-O-hexylchrysophanol derivatives having nucleic acid bases at position 5 were synthesized. Furthermore, derivatives of menadione substituted at position 11 (type A naphthoquinone derivatives) or methylmenadione substituted at position 7 (type B naphthoquinone derivatives) modified with nucleic acid bases, amines and thiocyano, selenocyano or thioacetyl groups were synthesized. The cytotoxic effects of these derivatives on HCT 116 cells, which poorly express P-glycoprotein (P-gp), and Hep G2 cells, which stably express P-gp, were evaluated by performing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Results were compared with those obtained using 5-fluorouracil (5-FU), which has been used clinically. Several of these derivatives exhibited markedly higher potent cytotoxic effects not only on HCT cancer cells but also Hep G2 cancer cells as compared with 5-FU.     

Redox flow batteries toward more soluble anthraquinone derivatives

The application of organic redox-active molecules in aqueous flow batteries demands a deeper understanding of how structures and electrolyte compositions determine solubility. Here we review recent work on anthraquinone derivatives to highlight key factors such as functional groups and counter ions. We discuss the prospect of further increasing solubility and outstanding issues in electrolyte design and solubility measurements.     

Solvatochromism of anthraquinone and symmetrical dihydroxy derivatives. Local interactions

The solvent effects on the electronic absorption spectra of 9,10-anthraquinone (AQ) and its symmetric dihydroxy derivatives namely 1,5-dihydroxyanthraquinone (1,5-DHAQ) and 2,6-dihydroxyanthraquinone (2,6-DHAQ) have been studied in pure solvents and some binary solvent mixtures. The frequencies of the absorption for AQ and 2,6-DHAQ are quite solvent sensitive while those for 1,5-DHAQ are not. Due to the intramolecular hydrogen bond between the CO and OH groups, no influence of solvent hydrogen bond acceptors is observed in 1,5-DHAQ. This hydrogen bond gives a stable six member cycle which is not broken even by the strongest hydrogen bond acceptor solvents used in this work, such as DMSO and DMF. The Taft and Kamlet's solvatochromic comparison method was applied for AQ and 2,6-DHAQ. Aromatic solvents and aliphatic amines were not included in the correlations since they strongly deviate suggesting another type of interactions. All the π→π^* bands of AQ and 2,6-DHAQ show strong influence of π^* despite the fact that their dipole moment is zero. Although it would be reasonable to expect that in the absence of a solute dipole moment there is not significant orientation of solvent molecules around the solute molecules, in this case dipolar interactions between solute and solvent due to local effects might be expected. AQ may be considered as formed by two carbonyl groups weakly interacting with the benzene rings; that means that the carbonyl group can behave as an isolated dipole and independently of the other. To detect possible specific interactions between the AQ and aliphatic amines and aromatic hydrocarbons, preferential solvation in mixed solvent was investigated. It is concluded that EDA interactions are important in the solvation of AQ with these compounds as solvents.     

Synthesis of novel,azasugar-modified anthraquinone derivatives and their cytotoxicity

A series of novel, azasugar-modified 2-monosubstituted, 2,6- and 2,7-bissubstituted anthraquinone derivatives have been synthesized by the nucleophilic substitution of N-alkylamino azasugar with mono-, bis（2-chloroacetamido）anthraquinones. Their cytotoxic activities against HeLa and MCF-7 ceils were preliminarily evaluated and compound 9a with mono-azasugar pendant at 2-position showed similar activity to the control drug （Cisplatin）.     

Relaxation times of aniline derivatives in cyclohexane and 1:4 dioxane

The permittivity (ε′) and dielectric loss (ε″) have been measured at 9.945 GHz for several substituted anilines in cyclohexane and 1:4 dioxane at 35°C. The static permittivity (ε_o) at 300 KHz and high frequency limiting permittivity (ε_∞) have also been measured at 35°C. The dielectric data have been used to yield mean relaxation times and apparent dipole moments. All the compounds studied exhibit an appreciably longer measured relaxation time in p-dioxane than in cyclohexane solution. This indicates that in solvent p-dioxane the free energy of activation for molecular reorientation is increased, probably by hydrogen-bond formation between an oxygen atom of the p-dioxane molecule and an amino-hydrogen atom of substituted anilines. Interaction is also apparent from the difference between their apparent dipole moments in the two solvents and may be dependent upon the volume of the molecule and the protonic character of the hydrogen atom of the amino-group within the substituted anilines. IR studies also confirm this viewpoint.     

A new heterocyclization in the series of acetylenic derivatives of anthraquinone

2-Alkynyl-l-amino-9,10-anthraquinones react with HNO₂ in a mixture of dilute HCl and dioxane at 20 °C to give I , 1-dichloroalkyl- IH-3-naphto[2,3-g]indazole-6,1 1 -diones. This reaction differs from the known cylization ofortho-alkynylbenzenediazonium salts involving the formation of a pyridazine ring (the Richter synthesis of 4-hydroxy- and 4-halocinnolines).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1803–1807, July, 1996,     

Condensation of o-diamino derivatives of anthraquinone and naphthoquinone with mesityl oxide

Anthraquinone- and naphthoquinonediazepines are formed by the reaction of 1,2- and 2,3-diamino-9,10-anthraquinones and 2,3-diamino-1,4-naphthoquinones with mesityl oxide. It was shown by spectral methods that naphthoquinonediazepine exists in two tautomeric forms.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 138–141, January, 1976.